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J. I. Ibarra


A new method to determine horizontal wind direction fluctuations σθ is presented based on the hypothesis of a Gaussian distribution of wind direction that gradually moves to a circular, uniform distribution under near-clam conditions. A theoretical formulation for σθ, the persistence of wind and the total horizontal standard deviation σ, is provided and supported by experimental observation both in a complex terrain valley site and in an open grassland spot in Spain. Comparisons of the proposed model with observations yielded a fairly good agreement making the theoretical functions a straightforward procedure for use in atmospheric dispersion calculations. The method also provides insights on either the residual diffusivity in near-calm conditions or the maximal observable standard deviation.

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Ricardo C. Muñoz, Mark J. Falvey, Mario Arancibia, Valentina I. Astudillo, Javier Elgueta, Marcelo Ibarra, Christian Santana, and Camila Vásquez


Over the past 15 years, Chile’s energy agencies have undertaken a series of projects aimed at evaluating the wind energy potential of the northern part of the country (western South America between 18° and 32°S), including the Atacama Desert. These projects have produced an unprecedented database of wind observations and ancillary meteorological data over an especially interesting climatic region, including more than 30 sites with 20-m meteorological masts and six high towers (60–80 m) with multilevel wind and temperature measurements. Measuring periods vary between 1 and 10 years, with about half the stations having 5 or more years of data. Site selection was guided by the results of a mesoscale numerical model, so the program provides a good example of modeling–observation interaction, as well as being a demonstration of a successful collaboration between government, university, and international assistance programs. This paper describes the publically available database of meteorological measurements, provides examples of regional climatological features revealed by the observations, compares observations with model results, and describes how the information provided by the program has contributed to the development of wind energy projects in the region.

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